Contact lenses have been used commercially to improve vision since the 1950s. The first contact lenses were made of hard materials. Although these lenses are currently used, they are not suitable for all patients due to their poor initial comfort and their relatively low permeability to oxygen. Later developments in the field gave rise to soft contact lenses, based upon hydrogels, which are extremely popular today. Many users find soft lenses are more comfortable, and increased comfort levels allow soft contact lens users to wear their lenses for far longer hours than users of hard contact lenses.
Despite this advantage, the extended use of the lenses can encourage the buildup of bacteria or other microbes, particularly, Pseudomonas aeruginosa, on the surfaces of soft contact lenses. The build-up of bacteria or other microbes is not unique to soft contact lens wearers and may occur during the use of hard contact lenses as well.
Therefore, there is a need to produce contact lenses that inhibit the growth of bacteria or other microbes and/or the adhesion of bacterial or other microbes on the surface of contact lenses. Further there is a need to produce contact lenses which do not promote the adhesion and/or growth of bacteria or other microbes on the surface of the contact lenses. Also there is a need to produce contact lenses that inhibit adverse responses related to the growth of bacteria or other microbes.
Others have recognized the need to produce soft contact lenses that inhibit the growth of bacteria. In U.S. Pat. No. 5,213,801, the production of an antibacterial contact lens is disclosed, where an antibacterial metal ceramic material is incorporated into a contact lens. This procedure contains a number of steps and may not be suitable for producing all types of lenses in a production environment. The steps include making a silver ceramic material that is fine enough to be used in a contact lens and then forming the lens with the powdered ceramic. However, lenses containing these types of materials often lack the clarity required by contact lens users.
U.S. Pat. Nos. 5,808,089; 5,902,818 and 6,020,491 disclose N-halamine type compounds and their use as biocides. Inclusion of these compounds in ophthalmic devices is not suggested. U.S. Pat. No. 6,162,452 discloses cyclic N-halamine biocidal monomers and polymers. Materials suitable for contact lenses are not disclosed.
Although these methods and lenses are known, other contact lenses that inhibit the growth and/or adhesion of bacteria or other microbes and are of sufficient optical clarity, as well as methods of making those lenses are still needed. It is this need, which this invention seeks to meet.